virus

Question 1

General Characteristics of Viruses

Answer 1

obligatory intracellular parasites (Cannot grow or replicate independent of a host cell)
-Contain DNA or RNA
* Contain a protein coat

Question 2

Viruses (not alive)

Answer 2

-Acellular (not cell-based)
-Are assembled; do not grow
-Cannot replicate independently; obligate
intracellular parasites

Question 3

Viruses (alive)

Answer 3

Are made of organic molecules (proteins; nucleic acid

Have the ability to take control of their host cell

They evolve over generations; ancestral lineage

Question 4

Bacteriophages

Answer 4

viruses that infect bacteria-

Most viruses infect only specific types of cells
in one host
* Determined by specific host attachment sites and
cellular factors

Question 5

Lytic replication

Answer 5

Viral replication usually results in death and lysis of the host
cell
– Five stages of lytic replication cycle
* Attachment
* Entry
* Synthesis
* Assembly
* Release

Question 6

Lysogenic cycle

Answer 6

 Phage lies latent until triggered to enter lytic cyle
 Bacteria does not die until phage enters lytic cyle
 After attachment and entry of the genome, phage
integrates into host chromosome as a prophage
 Trigger causes phage to enter lytic cycle with
biosynthesis, assembly (maturation), and releas

Question 7

Generalized transduction

Answer 7

Random bacterial
DNA is packaged inside a phage and transferred
to a recipient cell

Question 8

Specialized transduction

Answer 8

: Specific bacterial
genes are packaged inside a phage and
transferred to a recipient cell

Some very common bacterial exotoxins are passed via
specialized transduction
* Shiga toxin
* Diphtheria toxin
* Cholera toxin
* Botulinum toxin
* Scarlet fever toxin